ABSTRACT (Core C: Mouse Core) The overall goal of this Core laboratory is to provide the infrastructure, materials, animals, technical expertise and support that will facilitate the use of humanized immunodeficient mice in studies that examine HIV reservoirs in vivo. Recent advances have enabled the use of mice that lack their own immune system mice to be implanted with human tissue. Human tissue capable of developing into human immune cells is placed in the mice where it undergoes development into multiple types of human immune cells. The human tissue used in these studies is capable of a high degree of manipulation and experimentation in the mouse and the human cells, versus the mouse cells, are further susceptible to infection with HIV. This provides a powerful model to examine human blood cell development, to study the effects of HIV infection on human cells, and examine ways to purge HIV from immune cells. The generation of these humanized mice is a highly specialized procedure, due to the requirement for immunodeficient mouse strains, human hematopoietic tissue, infectious material, specialized facilities, and the necessary skill and knowledge to perform experiments in this system. This new core would represent a unique and valuable resource for this program, as the director of the Core has greater than 24 years of experience with humanized mouse models and the staff of the core have helped pioneer various novel techniques and findings in these models. In order for us to accurately assess and compare our results, standardization of the mouse model becomes absolutely critical. Thus, it is essential for this program, in order to draw the proper conclusions, that the studies involving humanized mice be standardized between laboratories. The central purpose of this core is to provide the specialized services and resources needed by all 3 projects in this program in the standardized fashion necessary to generate consistent and reliable data.